Vaccination Offers Protection From COVID Hospitalization, Severe Disease For 9 Months: Study

Despite Breakthrough Infections, Vaccines Offer Long-Lasting Protection From Worst Outcomes Of COVID-19

Vaccines are highly effective at keeping people out of the hospital due to severe COVID-19 and reducing death risk, says a new study.

Cases of Omicron are surging worldwide, even infecting those who are fully vaccinated and boosted. Researchers have been suggesting that breakthrough infections are due to waning of vaccine-induced antibody levels and the new variants of concern like omicron are also better at evading existing antibodies. But vaccination can still offer long-lasting protection from the worst outcomes of COVID-19, a new study reiterated.

Despite breakthrough infections, COVID-19 vaccines can offer protection from hospitalization and severe disease for as long as nine months after getting the first shot, said researchers from the University of North Carolina at Chapel Hill who conducted the study. The results of the study were published in the New England Journal of Medicine.

“Unvaccinated people should get vaccinated right away,” said lead study author Danyu Lin, PhD, Dennis Gillings Distinguished Professor of Biostatistics at the UNC Gillings School of Global Public Health.

For the study, the UNC-Chapel Hill collaborated with the North Carolina Department of Health and Human Services.

Vaccines effective at keeping people out of hospitals

The findings are based on the examination of data on COVID-19 vaccination history and health outcomes for 10.6 million North Carolina residents, carried out between December 2020 and September 2021.

According to their study results, the effectiveness of the Pfizer and Moderna mRNA vaccines in reducing the risk of COVID-19 reached a peak of about 95 per cent at two months after the first dose and then gradually declined. At seven months, the Pfizer vaccine effectiveness dropped to 67 per cent but effectiveness of Moderna vaccine remained at 80 per cent. The study found that effectiveness for the Johnson & Johnson adenovirus vaccine to be 75 per cent at one month after the first dose, but then it fell to 60 per cent after five months.

All three vaccines were highly effective at keeping people out of the hospital due to severe COVID-19. Effectiveness of the Pfizer vaccine in reducing COVID-19 hospitalization reached a peak of 96 per cent at two months and remained around 90 per cent at seven months. Effectiveness of the Moderna and Johnson & Johnson vaccines reached a peak of 97 per cent and 86 per cent respectively at two months, and their efficacy remained at 94 per cent and above 80 per cent respectively through six months.

For all three vaccines, effectiveness in reducing death due to COVID-19 was higher than that of hospitalization.

Study supports use of boosters

The study also underscored the importance of booster shots to provide ongoing prevention of hospitalization and death from COVID-19, especially for older adults. The authors noted that the Centers for Disease Control and Prevention (CDC) have used their study results to support the use of booster shots.

The authors supported the theory that declining immunity is responsible for breakthrough infections. “Because the majority of the vaccines in the U.S. were administered more than seven months ago and only a small percentage of the population has received boosters, waning immunity is likely contributing to the breakthrough infections with the omicron variant,” Lin said, as quoted by Science Daily.

Understanding vaccine effectiveness is critically important in determining the optimal timing of booster vaccination, the researcher added.